Sheet mis-feed detection means



Dec. 27, 1960 s. E. CALHOUN 2,966,355

- SHEET MIS-FEED DETECTION MEANS FiLed Feb. 18, 1959 2 Sheets-Sheet 1 5 INVENTOR.

i 54/0061. 5. CnL/founl 0 4 ATTORNEY Dc. 27, 1960 s. E. CALHOUN 2,966,355

SHEET MIS-FEED DETECTION MEANS Filed Feb. 18, 1959 2 Sheets-Sheet 2 14;! j INVENTOR.

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ZTTOR United States Patent SHEET MIS-FEED DETECTION MEANS Samuel E. Calhoun, Springtlale, Conn., assignor to Pitney- Bowes, Inc., Stamford, Conn., a corporation of Delaware Filed Feb. 18, 1959, Ser. No. 794,031

8 Claims. (Cl. 27157) This invention relates to sheet feeding devices, and more particularly, to the detection of the mis-feeding of sheets by such devices.

In the operation of sheet feeding devices, a mis-feed may occasionally occur due, for example, to improper adjustment of the feeding device. It is desirable to detect mis-feeds so as to ensure that a sheet has been properly fed each time one is due and to prevent damage to such a device or to the sheets being fed. Such a misfeed could occur as a non-feed whereby one of a succession of sheets fails to be fed or as a partial-feed whereby one of a succession of sheets is fed short of the intended extent.

It is accordingly an object of this invention to provide new and improved means for detecting the mis-feeding of sheets by feeding devices. A further object is to provide such means including a feeler member having a sensing portion for detecting mis-feeds, which portion is'effective in operation even though it may be fouled with dust, dirt or material with which the sheets are coated, etc.

Another object of the invention is to provide improved means for detecting the partial-feeding as well as the non-feeding of sheets by feeding devices.

A further object of this invention is to provide such means which is compact, simple, dependable in operation and inexpensive to produce.

Further objects and advantages will become apparent as the description proceeds.

In the accompanying drawings, a preferred embodiment of the invention is shown wherein:

Fig. 1 is a part sectional and part side elevational view of a sheet feeding apparatus including means according to the invention for detecting a mis-feeding thereof, this view being taken along line 1--1 in Fig. 2 and showing the position of the respective parts upon the occurrence of a non-feed;

Fig. 2 is a fragmentary front sectional and elevational view taken along lines 22 in Fig. 1 and including por' tions of the means for advancing sheets fed by the sheet feeding apparatus;

Fig. 3 is a fragmentary view similar to Fig. 1 but with certain of the parts omitted for clarity of illustration and showing one position of respective parts during feeding of a single sheet;

Fig. 4 is a fragmentary view similar to Fig. 3 but with additional parts omitted and showing the position of respective parts just after proper feeding of a single sheet;

Fig. 5 is a fragmentary view similar to Fig. 4 but on a smaller scale and further including means for advancing sheets fed by the sheet feeding means, the sheet advancing means being depicted just prior to its gripping a properly fed sheet;

Fig. 6 is a fragmentary view similar to Fig. 4 but showing the position of respective parts upon the occurrence of a partial-feed;

Fig. 7 is a schematic wiring diagram showing an electrical connection of the detecting means of the inven- 2,966,355 Patented Dec. 27, 1960 tion for effecting the indication of a mis-feed by the sheet feeding means; and

Fig. 8 is a fragmentary perspective view of the lower end portion of the means included in Fig. 1 for detecting a mis-feed.

According to the embodiment of the invention as shown in the accompanying drawings, sheets are fed one by one from feed rollers to a normal position at which each sheet has its trailing end portion resting on a ledge while its leading end engages stop means. After each sheet is due to have been fed, a test is made to determine whether or not a sheet is properly-in said normal position. It so, the sheet is advanced from the normal position and, if not, the machine is stopped.

Testing is accomplished by a feeler member moved, in timed relation with the sheet feeding means, from a retracted location out of the feeding path of the sheets to an advanced location adjacent said ledge. If a sheet is in said normal position when the feeler member is in said advanced location, engagement of the feeler member with the trailing end portion of the sheet will cause a movable contact carried by the feeler member to assume a contacts-open position between a pair of other electrical contacts. If, instead, a non-feed should have occurred such that no trailing end portion of a sheet rests on said ledge, said movable contact, which normally engages one of the contacts of said pair, will remain in contactsclosed position. Furthermore, if a partial feed should have occurred i.e., an incomplete feed which leaves the trailing end portion of the sheet curled above the ledge, said feeler member will engage the sheet above the ledge causing the movable contact to move into contacts-closed relation with the other contact of said pair.

Associated with the feeler member is a timing device which completes an electrical circuit while the feeler member is in said advanced location so long as the feeler member is in either of said contacts-closed positions, thereby to power cut-off control means so as to stop the drive of the machine. If a sheet has been properly fed to said normal position, the movable contact carried by the feeler member will be moved to. said contacts-open position as noted above, thereby preventing said timing device from completing said electrical circuit and permitting the sheet to be advanced from said normal position.

Referring to Fig. 1, a sheet feeding device is generally designated at 10. The sheet feeding device is operable to feed sheets S one by one from a hopper, 12 to the position shown in Fig. 4 at which the leading end of each successive sheet engages a pair of laterally spaced stops 14 (only one of which is shown) and the trailing end portion of the sheet rests on the upper surface of a ledge 16. The embodiment as shown in the drawings further includes sheet advancing means generally designated at 18 (see particularly Figs. 2 and 5) which includes a pair of gripper devices 20 for gripping individual sheets properly fed to the position shown in Fig. 4 and for advancing the gripped sheets past the location of the stops 14 which will have been retracted-below the level of the leading end of the previously fed sheet in timed relation with the sheet advancing means.

Referring to Figs. 1 and 2, the sheet feeding device 10 includes a main feed roller 22 and a pair of presser rollers 24 which are intermittently operable to effect the feeding therebetween of sheets one by one to the position shown in Fig. 4. A starting roller 26 is cooperable with an abrasive surfaced roller or abutment 28 to deliver the leading edge of the next succeeding sheet S into the nip of rollers 22, 24 just after the latter have stopped subsequently to feeding of a sheet to the position shown in Fig. 4. A pair of booster rollers 30, 30 is provided for maintaining the leading end of the foremost sheet S in hopper 12 in position to be engaged and driven by starting roller 26. For further details of the structure and function of the sheet feeding means 10, reference is hereby made to U.S. Patent 2,762,623 to F. W. Uthenwoldt et al.

Ledge 16 is provided by a forwardly extending member 17 carried by the supporting base 32 of the machine by means such as screws 33. Each stop 14 is carried by a supporting means 34 for movement from the advanced position shown in Figs. 3, 4 and 6 to the retracted position below the level of the leading end of a fed sheet S as shown in Fig. 5.

Each gripper device 20 of sheet advancing means 18 includes a shelf 36 against which the trailing end portion of one or more sheets S is retained by a gripping finger 38 yieldingly urged in the clockwise direction as viewed in Fig. about a pivot 40. Each gripper 20 is supported by a sprocket chain 42 for intermittently moving the former in timed relation to the feeding of sheets to the position shown in Fig. 4. As the sheet advancing means 18 moves to the position shown in Fig. 5, a cam follower roller 44 rotatably carried by a rearward extension of each gripping finger 38 will have come into engagement with a cam 46 carried by base 32 thereby to depress the cam follower roller 44 and elevate the gripper finger 38 to open position. As the sheet advancing means 18 continues to move in the direction of the arrow in Fig. 5, an upstanding end wall 48 of each gripper member 20 will move into engagement with the trailing end of the sheet S as shown in this figure to move the trailing end portion of this sheet off and past ledge 16, after which the cam follower roller 44 rides oif the end of its cam 46 whereby the respective gripper finger 38 moves downwardly under said resilient bias to grip the sheet S and two previously collected sheets S against shelf 36 as shown in Fig. 5. The two previously collected sheets will have been taken by sheet advancing means 18 from two sheet feeding devices identical to that described above and located rearwardly thereof. The machine may further include envelope stufiing means by which the several sheets S collected by sheet advancing means 18 are inserted into an envelope. For further details of the structure and function of the sheet advancing means 18 and such an envelope stuffing unit, reference is hereby made to U.S. Patent No. 2,736,999 to F. J. Rouan et al.

During the course of operation of the sheet feeding device 10, a mis-feed may occasionally occur. Such a misfeed could occur as a non-feed whereby the sheet feeding means fails to feed a sheet S to the position shown in Fig. 4 when due. This is depicted in Fig. 1, it being noted that in this figure no sheet S is properly disposed with its trailing end portion resting on the upper surface of ledge 16. Such a misfeed could also occur as a partial-feed whereby the leading edge of sheet S is fed short of engagement with stops 14, in which case the trailing end portion of the sheet will be disposed in curled position above ledge 16, all as depicted in Fig. 6.

For detecting such non-feeds and partial-feeds, a pair of laterally spaced mis-feed detector members 50 and 50a are provided. Detector members 50 and 50a are or may be identical mirror-image counterparts of each other and a description of one will suffice for both. It will be understood, therefore, that each reference numeral in the accompanying drawing having a letter a afiixed thereto refers to a part or structure which is identical in function to and a mirror-image of the counterpart -bearing the same reference numeral absent the letter a.

Detector member 50 includes an upper leg portion 52 and a lower leg portion 54, the latter being hingeably connected for pivotal, knee-action movement about a pin 56 carried by the former. A torsion spring '58 is coiled about pin 56, has one end engaged with a stop pin 60 carried by upper leg 52, and its other end engaged with apin 62 carried by lower leg 54. With this arrangement, lower leg 54 ordinarily remains fixed in the pivotal position relative to upper leg 52 as shown in Figs. 1 through 3 at which an extension 64 carried by the former engages the stop pin 60 carried by the latter. If a misoperation should occur at any time resulting in movement of one or more sheets forwardly against lower leg 54, this leg will pivot about pin 56 against the bias of spring 58 thereby avoiding damage to the detector and parts associated therewith.

Upper leg 52 also carries another pin 66 to which one end of an arm 68 is loosely pivotally connected, the other end of arm.68 carrying a hub 70. A cross bar 72 is supported by side walls 74 (only one of which is shown in Fig. l) of the sheet feeding device and extends through the aperture provided by hub 70 thereby loosely to mount arm 68 for pivotal movement thereabout. Upper leg 52 of detector member 50 further carries a reversely bent extension 76. A screw 78 extends through an aperture in extension 76, and into threaded engagement with a boss 86 fixedly carried by extension 76. By 'threadedly adjusting screw 78 and tightening down a lock-nut 81, screw 78 is adjustably positioned relative to arm 68 thereby to limit the downward pivotal movement of arm 68 relative to upper leg 52 by the engagement of arm 68 with the head of the screw.

The lower leg 54 of detector member 50 has integral therewith or otherwise fixedly carries a hold-down foot member 84. Lower leg 54, hold-down member 84 and the remaining parts of detector member 50 are movable back and forth between the retracted location shown in Fig. 3 and the advanced location shown in Fig. l in timed relation with the feeding of sheets. For effecting this movement of detector member 50, a rocker shaft 86 is provided, the latter being journalled in side walls 74 for rocking movement about its axis. Shaft 86 is rocked back and forth in the clockwise and counterclockwise directions about its axis by means of a driving link 88 which is fixedly connected thereto and which is connected through power take-off means (not shown) to the motive means which powers the machine. An arm 90 is fixedly carried by rocker shaft 86 for reciprocating pivotal movement thereabout. The distal end of arm 90 carries a pin 92 extending through an elongated slot 94 provided by lower leg 54 of the detector member 50. Pin 92 has one end connected to a comparatively light tension spring 96, the other end of which is connected to pin 56 carried by upper leg 52 of detector member 50. With the respective parts in the retracted location shown in Fig. 3, arm 90 will be pivoted about the axis of rocker shaft 86 in the counter-clockwise direction as viewed in this figure to move pin 92 downwardly thereby exerting through spring 96 a pulling force on pin 56 which, along with the weight of detector 50, causes pivotal movement of arm 68 about the axis of cross bar 72 and relative pivotal movement between arm 68 and upper leg 52. The result is movement of the lower end of detector 50 first generally rearwardly (to the left as viewed in Figs. 1 and 3) and then generally downwardly to the advanced position shown in Fig. l at which the head 82 of screw '78 comes into engagement with arm 68 thereby to prevent further movement of the lower end of detector 50 from the retracted position. When detector 50 reaches the fully advanced position, arm 90 ordinarily continues to move in the counter-clockwise direction with lost-motion of pin 92 along slot 94 and relative to detector 50.

With a sheet S in the properly fed position and with detector 50 in the fully advanced position, all as shown in Fig. 4, hold-down member 84 will be engaged with and will retain the trailing end portion of the sheet on ledge 16. The comparatively light force exerted against the sheet by the hold-down member due to the light yield ing force exerted by tension spring 96 permits grippers 20 to advance the sheet ofi the ledge while the holddown member remains in fully advanced location. After the sheet advancing means has moved the trailing end portion of a fed sheet oif and past ledge 16, and before the leading end of the next succeeding sheet has been fed across the path of movement of hold-down member 84 between its advanced and retracted locations, arm 90 will pivot in the clockwise direction to move pin 92 against the upper end of slot 94 thereby to move detector 50 to the fully retracted location as shown in Fig. 3.

Detector 50 includes a feeler member generally designated at 100 and having a rearwardly extending portion 102 and a rearwardly extending foot 103. Portion 102 and foot 103 are interconnected by a yoke 105, and foot 103 provides a sensing surface portion 104. A lever 106 of feeler member 100 extends at a substantial angle to foot 103 and terminates in a movable electrical contact 108. A torsion spring 110 (see Fig. 2) yieldingly urges feeler member 100 in the counterclockwise direction as viewed in Figs. 1, 3, 4 and 6 about a pin 112 which extends through apertures in portion 102 and foot 103 and which is carried by lower leg 54 of detector member 50. Lower leg 54 also carries a block 114 of electrical insulation material such as one of the customary plastics. Block 114 mounts a U-shaped member 116 in electrically insulated relationship to lower leg 54. U-shaped member 116 is formed of electrically conductive material and the two legs thereof form two electrically connected, electrical contacts 118 and 120, respectively. Contact 118 is engaged by movable contact 108 when the feeler member is in the full counter-clockwise position toward which it is urged by spring 110, and contact 120 is engaged by the movable contact when the feeler member is moved to the fully clockwise position. It will be recognized that when feeler member 100 is intermediate said two positions neither of the contacts 118 and 120 will be engaged by movable contact 108. A flexible lead 122 electrically connects and grounds both of contacts 118 and 120 to the base of the machine.

By timed means later to be described, the motive power of the entire machine will be cut off when the detector 50 is in advanced location and the movable contact 108 is in contacts-closed relation with either of contacts 118 and 120, thereby indicating the occurrence of a mis-feed.

Ledge 16 provides an open-ended slot 124 directly below and cooperable with surface portion 104 of feeler member 100 in the same manner as a similar slot 124a is directly below and cooperable with the sensing surface portion of the feeler member of detector 50a. When the trailing end portion of a properly fed sheet lies on ledge 16 it spans and covers slots 124 and 124a.

As shown in Fig. 3, sensing surface portion 104 extends below and rearwardly of hold-down member 84 when feeler member 100 is in the fully retracted location and the fully counter-clockwise pivotal position about pin 112. When detector 50 moves to the advanced location to bring hold-down member 84 into engagement with the trailing end portion of a properly fed sheet S as shown in Fig. 4, the sensing surface portion 104 of feeler member 100 precedes the hold-down member in coming into engagement with said trailing end portion and is restrained from moving past the upper surface of the ledge by engagement with that trailing end portion. The contact 108 is therefore pivoted, with the remainder of feeler member 100, against the bias of torsion spring 110 to an intermediate pivotal position at which it is disengaged from both of contacts 118 and 120. When detector 50 moves to the advanced location after a non-feed occurs as depicted in Fig. 1, no trailing end portion of a sheet will lie on ledge 16 to cover slot 124 therein. The sensing surface portion 104 will therefore move into slot 124 and past the upper surface of the ledge, and feeler member 100 will remain in the fully counter-clockwise pivotal position at which movable contact 108 is engaged with contact 118. During movement of detector 50 toward the advanced location after a partial feed occurs as shown in Fig. 6, the trailing end portion of the sheet will be curled above ledge 16 and sensing surface portion 104 will engage the sheet causing pivotal movement of feeler member to the fully clockwise position at which movable contact 108 engages contact 120.

Briefly to recapitulate, movable contact 108 will be engaged with one of contacts 118 and 120 when detector 50 is in advanced location and either a non-feed or a partial-feed has occurred whereas movable contact 103 will be disengaged from both of contacts 118 and 120 when detector 50 is in advanced location and proper feeding of a sheet S has occurred.

Contacts 108, 118 and 120 are electrically connected in a manner now tobe described for stopping operation of the entire machine upon the occurrence of a non-feed or a partial-feed. Referring to the schematic wiring diagram of Fig. 7, feeler member 100 is electrically connected (through detector 50) to a signal lamp 126 and an electromagnetic switch 128, the latter two being electrically connected in parallel circuit relation with each other. As noted in Fig. 1, lamp 126 may conveniently be mounted on one of side walls 74. Lamp 126 and electromagnetic switch 128 are, in turn, electrically connected in succession through a manually operated on-off switch 130, a make-and-break switch 132 which is cycled between opened and closed positions by a continuously rotating timing cam 134, an electrical current source 136, and then to ground. When electromagnetic switch 128 is energized, normally closed contactor 138 thereof moves to open-circuit position thereby to de-energize the motive means 140 which drives the entire machine. As previously noted, contacts 118 and 120 are electrically grounded through flexible lead 122 to the base of the machine. Battery 136 is likewise electrically grounded to the base of the machine.

In operation, switch will be closed to render the machine-stopping means operative. Timing cam 134 is continuously rotated in timed relation with the sheet feeding means 10 and detector 50 so that switch 132 will be closed for a significant time interval after detector 50 has moved to the fully advanced location and before the trailing end of a sheet S, which ordinarily will be lying in properly fed relation on ledge 16, is due to be advanced ofi the ledge by the sheet advancing means 18. As is apparent from Fig. 7, with switch 130 closed feeler member 100 is rendered electrically live when switch 132 is closed. If either a non-feed or a partialfeed has occurred, feeler member 100 will be electrically connected to either of contacts 118 and 120 whereby lamp 126 will be lighted and electromagnetic switch 128 will be energized to stop operation of sheet feeding means 10 as well as the rest of the entire machine.

The provision of a pair of detectors 50 and 50a, respectively, is advantageous for the reason, among others, that a sheet could be fed askew so that one side of a trailing end portion lay on the ledge 16 to cover one of the slots, 124, for example, but the other side did not cover slot 124a. In this case, a single detector 50 would not detect this mis-feed but, of course, the other detector 50a would.

Because movable contact 108 and contacts 118 and 120 are remote from sensing surface portion 104, these contacts will continue to provide their intended functions even though sensing surface portion 104 may become fouled with dust, dirt, material of which the fed sheets are coated, etc. This is in contra-distinction to and an improvement over other arrangements such, for example, as those by which a sensing surface portion electrically contacts another surface to establish an electnical circuit.

Since many changes could be made in the embodiment of the invention particularly described and shown herein without departing from the scope of the invention, it is intended that this embodiment be considered as exemplary and that the invention not be limited except as warranted by the following claims.

What is claimed is:

1. In combination: a ledge; means for feeding sheets one by one to move the trailing end portions thereof successively onto said ledge preparatory to the advancement of said sheets one by one to move the trailing end portions thereof successively off said ledge; a feeler member yieldingly urged from a first position spaced from said ledge to a second position past said ledge; said feeler member being moved to a position intermediate said first and second positions when engaged with one of said trailing end portions of a sheet properly located on said ledge, being disposed in said second position when no trailing end portion of a sheet is located on said ledge, and being moved to said first position by engagement with a sheet whose trailing end portion is improperly located above said ledge; electrical contact means associated with said feeler member for movement to contactsolosed relation when said feeler member is moved to either of said first or second positions and for movement to contacts-open relation when said feeler member is moved to said intermediate position; and means operatively associated with said electrical contact means for stopping operation of said sheet feeding means when the contact means is in contacts-closed relation.

2. In combination: a ledge; means for feeding sheets one by one to move the trailing end portions thereof successively onto said ledge preparatory to the advancement of said sheets one by one to move said trailing end portions thereof successively olf said ledge; a feeler member having a surface yieldingly urged from a first position spaced from said ledge to a second position past said ledge: said surface of the feeler member being moved to a position intermediate said first and second positions when engaged with one of said trailing end portions of a sheet properly located on said ledge, being disposed in said second position when no trailing end portion of a sheet is llocated on said ledge, and being moved to said first position by engagement with a sheet whose trailing end portion is improperly located above said ledge; a pair of electrical contacts; a movable third electrical contact operatively associated with said feeler member for engagement with one of the contacts of said pair when the feeler member is in said first position, for engagement with the other contact of said pair when the feeler member is in said second position and for disengagement from the contacts of said pair when the feeler member is in said intermediate position; and means for stopping operation of said sheet feeding means when said third movable contact is engaged with either of the contacts of said pair.

3. In combination: means providing a surface on and past which sheets are adapted to be fed along a first path; a feeler member; means for moving said feeler member from a retracted location to an advanced location; a portion of said feeler member being spaced to one side of said surface when the feeler member is in retracted location and said portion being moved along a second path intersecting said first path to a position past said surface when said feeler member is moved to said advanced location and none of said sheets is disposed at the intersection of said first and second paths; and said last-named means including a yieldable connection permitting said portion of the feeler member to be restrained from moving past said surface by engagement thereof with one of said sheets disposed at the intersection of said first and second paths; and means operatively associated with said feeler member for indicating whether or not said portion of the latter is so restrained; said last-mentioned means comprising cooperating electrical contacts located remote from said first path and operatively connected to be tripped by said feeler member when said portion is so restrained.

" tein-combination: a ledge; means for feeding sheets one by one to move the trailing end portions thereof'successively onto said ledge preparatory to the advancement of said sheets one by one to move the trailing end portions thereof successively oif said ledge; a feeler member; means mounting said feeler member for movement, in timed relation with said feeding means, from a retracted location out of the feed path of said sheets to an advanced location adjacent said ledge; yieldable means permitting movement of said feeler member from a first position to a second position relative to said mounting means upon engagement of the feeler member, when in said advanced location, with a trailing end portion properly located on said ledge; a pair of normally closed electrical contacts operatively connected with said feeler member for movement relative to each other to contactsopen relation when said feeler membenmoves to said second position; said yieldable means retaining said feeler member in said first position relative to said mounting means when said feeler member is in said advanced location and no trailing end portion is located on said ledge; and means operatively associated with said contacts for stopping operation of said feeding means when said contacts are in closed relation and said feeler member is in said advanced location.

5. In combination; means providing a surface on and past which sheets are adapted to be successively fed; a hold-down member; means mounting said hold-down member for movement from a retracted location to an advanced location; a feeler member carried by said holddown member; yieldable means urging said feeler member from a first position to a second position relative to said hold-down member; said hold-down member, when in said advanced location, retaining each of the successively fed sheets on said surface; said feeler member, when the hold-down member moves to said advanced location, being disposed in said second position relative to said holddown member and including a portion movable past said surface so long as no sheet is located on said surface, said feeler member being moved to said first position relative to said hold-down means by engagement of said portion with a sheet properly located on said surface; and means operatively associated with said feeler member for indicating whether or not the latter is in said second position; said last-mentioned means comprising cooperating electrical contacts located remote from said surface and operatively connected to be tripped by said feeler member when said portion is so restrained.

6. In combination: a ledge; a stop; sheet feeding means for intermittently feeding sheets one by one to move the leading edges thereof into engagement with said stop and the trailing end portions thereof onto said ledge preparatory to one by one movement of said leading edges and said trailing end portions past said stop and off said ledge, respectively; a feeler member; means mounting said feeler member for successive movement between retracted and advanced locations in timed relation to the feeding of the successive sheets so as to be in advanced location when each trailing end portion is due to be disposed on said ledge; means yieldably urging said feeler member from a first position to a second position relative to said mounting means and past said ledge when in said advanced location and no trailing end portion is located on said ledge; said feeler member, upon movement to said advanced location, being moved relative to said mounting means to said first position by engagement with a sheet whose trailing end portion is improperly located above said ledge and being moved relative to said mounting means to a position intermediate said first and second positions by engagement with a trailing end portion properly located on said ledge; and means operatively associated with said feeler member for stopping operation of said sheet feeding means when said feeler member is in either of said first and second positions upon movement thereof to said advanced location.

7. In combination: a ledge; a stop; sheet feeding means for intermittently feeding sheets one by one to move the leading edges thereof into engagement with said stop and the trailing end portions thereof onto said ledge preparatory to further intermittent feeding of said sheets one by one successively to move said leading edges and said trailing end portions thereof past said stop and off said ledge, respectively; a feeler member; means mounting said feeler member for successive movement between retracted and advanced locations in timed relation to the feeding of the successive sheets so as to be in advanced location when each trailing end portion is due to be disposed on said ledge; means yieldably urging said feeler member from a first position to a second position relative to said mounting means; said feeler member, upon movement to said advanced location, being moved relative to said mounting means to said first position by engagement with a sheet whose trailing end portion is improperly located above said ledge, being moved relative to said mounting means to a position intermediate said first and second positions by engagement with a trailing end portion properly located on said ledge, and being disposed in said second position past said ledge when no trailing end portion is located on said ledge; electrical contact means associated with said feeler member for movement to contacts-closed relation when said feeler member is moved to either of said first or said second positions and for movement to contacts-open relation when said feeler member is moved to said intermediate position; and means operatively associated with said contact means for stopping operation of said sheet feeding means when the contact means is in contact-closed relation and said feeler member is in said advanced location.

8. In combination: a ledge; a stop; sheet feeding means for intermittently feeding sheets one by one to move the leading edges thereof into engagement with said stop and the trailing end portions thereof onto said ledge preparatory to one by one movement of said leading edges and said trailing end portions past said stop and off said ledge, respectively, a feeler member; a hold-down member; means mounting said feeler member and said holddown member for successive movement between retracted and advanced locations in timed relation to the feeding of the successive sheets so as to be in advanced location when each trailing end portion is due to be disposed on said ledge; said hold-down member, when in advanced location and one of said trailing end portions is properly located on said ledge, retaining the trailing end portion against the ledge; means yieldably urging said feeler member from a first position to a second position relative to said mounting means and past said ledge when in said advanced location and no trailing end portion is located on said ledge; said feeler member, upon movement to said advanced location, being moved relative to said mounting means to said first position by engagement with a sheet whose trailing end portion is improperly located above said ledge and being moved relative to said mounting means to a position intermediate said first and second positions by engagement with a trailing end portion properly located on said ledge; electrical contact means associated with said feeler member for movement to contacts-closed relation when said feeler member is moved to either of said first or second positions and for movement to contacts-open relation when said feeler member is moved to said intermediate position; and means operatively associated with said feeler member for stopping operation of the sheet feeding means when the contact means is in contacts-closed relation and said feeler member is in said advanced location.

References Cited in the file of this patent UNITED STATES PATENTS 1,468,754 Smith Sept. 25, 1923 2,709,960 Alix et al. June 7, 1955 2,711,896 Kleineberg et a1 June 28, 1955 

